Flexible piston ring



July 14, 1953 H. F. PRASSE FLEXIBLE PISTON RING Filed Jan. 24, 1950 Patented July 14, 1953 FLEXIBLE PISTON RING Herbert F. Prasse, Gates Mills, hio, assignor to Thompson Products, Inc., Cleveland, Ohio, a

corporation of Ohio Application January 24, 1950, Serial No. 140,3.00

7 Claims.

This invention relates to improvements in piston rings and more particularly relates to an improved oil control piston ring which may be made from strip steel.

It has heretofore been a common practice to construct oil control piston rings which have a plurality of vertically spaced circumferential oil scraping edges bearing against the wall of a cylinder during reciprocation of a piston therein. The space between the oil scraping edges serves as a reservoir for collecting oil removed from the cylinder wall by the scraping edges, and oil passages through the web or back of the ring connect this space with the back of the piston ring groove and return the cil through radial openings in the piston leading to the crankcase. Such oil control piston rings have also been formed from continw uous strip steel by a series of blanhing, forming and heat treating operations followed by relatively difiicult and expensive nnishing operations.

In accordance with my present invention, I provide a plurality of scraping edges or scavenger elements but stop these elements short of the oil passages of the ring, so as to provide a relatively rigid semi-segmental type of scavenger element construction having suflicient iieXi-bility to enable the ring to conform to the cylinder wall, but being rigid enough to permit the ring to be finished with the same kind of tooling as is used on standard type cast iron rings.

The principal object of my invention is to provde a simple and improved form of oil control piston ring which may be made from strip steel and may be machined in the same manner as standard types of cast iron piston rings.

A further object of my invention is vto provide a new and improved form of oil control piston ring which may be inexpensively made from strip steel and which is so constructed as to eliminate many of the manufacturing difficulties heretofore encountered in the manufacture of piston rings from continuous strip stock.

A still further object of my invention is to provide a simple, cheap, eiiicient and easily installed oil control piston ring maintaining a plurality of scavenger elements in vertically and circumferentially spaced relationwithin va cylinder during all positions which may be assumed by the piston ring in operation in a cylinder.

These and other objects of my invention will appear from time to time as the following specication proceeds and with reference to the accompanying drawing wherein: I

Figure l is an enlarged fragmentary plan view of a flexible oil piston ring constructed in accordance with my invention;

Figure 2 is an enlarged fragmentary plan view of the ring shown in Figure 1;

Figure 3 is a transverse sectional View taken substantially along line III-III of Figure 1;

Figure 4 is an enlarged fragmentary view showing a modied form in which my invention may be embodied; and

Figure 5 is a transverse sectional view taken substantially along line V-V of Figure Ll.

Referring now more particularly to the drawing illustrating a preferred embodiment of oil control ring constructed in accordance with my invention, numeral l0 indicates an oil control ring made up from fiat strip steel stock and having a web l l of a ladder-like form having cross bars lZ-IZ connecting parallel annular scraping or scavenger anges l3-l3 together. Transverse slots ill-ill between the cross bars |2-|2 form oil passages extending radially of the ring and connecting the channel of the ring formed between the flanges lli-i3 with the back of the annular piston ring groove formed in the piston (not shown), to return oil to the crankcase through the oil return passages in the piston.

The piston ring may be formed from flat strip stock of tool steel, such as S. A. E. 1095 containing 0.95% carbon which maybe hardened after the blanking and forming operations thereof. In order to impart flexibility to the ring without forming separate segments, a series of equally spaced slits or cuts l5-l 5 are made in the flanges l3-l3 from the outer sides thereof, the slits on opposite flanges preferably being aligned and registering with the centers of the slots lll-lll. The slits {5e-45 may be made in the fiat strip during the blanking operation, before formation of the ring in a circular form of U-shaped cross-section. In order to relieve the inner ends Iof the slits l5-l 5 and the flanges EB-l 3 from undue stresses, the slits 5-l5 are herein shown as terminating in circular holes l6-l, which may be placed in the flat strip either during or just prior to the cutting or slitting operation. It should here be noted, however, that while I have shown the slits l5-|5 relieved by the circular holes l6-5 that said holes need not be circular, and need not be in all sizes and types of rings, but are considered to be especially desirable for the smaller diameter rings. It should further `be noted that in Figure 2 the slits l5-l5 are exaggerated and shown as being of a substantially V-shaped formation by reason of the spreading apart of the scraping edges when forming the ring to a circular form. In the form of my invention shown in Figures l and 5, I show a fragment of a ring much like the piston ring shown in Figure l. This ring,

however, has flanges i9 which are thinned and elongated toward their outer edges. This may be done during the operation of forming the ring by a rolling operation after slitting of the flanges and makes opposite sides of the slits substantially parallel when the strip is formed to the annular circular form it will assume when in the piston and cylinder of an internal combustion engine.

In order to give the ring the correct wall pressure against the walls of the cylinder anV eX- pander may be carried in the channel between the flanges |3--l3 to yieldably force the ends of the ring apart. As herein shown, I preferably use a leaf-type expander I7 of a substantially looped-shaped formation substantially conforming to the radius of curvature of the ring and having an open inner central portion, the adjacent ends of which are outturned, as indicated by reference character I8, to engage the adjacent ends of the adjacent cross bars I 2-|2, and yieldably force the ends of the ring apart.

It may be seen from the foregoing that an improved oil control piston ring has been provided, which is cheap to manufacture, and is of an efficient and of durable construction. It may further be seen that the ring may be formed from flat strip steel stock and has a plurality of vertically spaced circumferential scavenging surfaces slidably engaging the walls of the cylinder and wiping the oil therefrom, for return to the crankcase through the oil return passageways formed in the ring and piston, and that these wiping surfaces are formed and flexibility of the ring is attained by slitting the ring radially at a plurality of equally spaced points partially through the flanges thereof, rendering the ring sufficiently flexible to conform to the form of the cylinder, but rigid enough to permit the ringto be finished after the blanking, forming and heat treating operations by the same type of tooling used to finish standard types of cast iron piston rings. It may further be seen that the ring of my invention affords far a simpler oil control ring than heretofore and provides a more accurate oil control ring which may be made from fiat strip steel stock, but which retains the desirable features of cast iron piston rings.

It will be understood that modifications and variations may be effected without departing from the scope of the novel concepts of the present invention.

I claim as my invention:

l. A piston ring comprising a slotted annular web having spaced annular flanges extending from opposite sides thereof, and a plurality of circumferentlally spaced radial slits in said flanges opening to the outer periphery of the ring and terminating outwardly from said slots and imparting flexibility to the ring.

2. A piston ring comprising a slotted annular web having spaced annular flanges extending from opposite sides thereof, and a plurality of vertically registering circumferentially spaced slits in said flanges extending inwardly from the outer sides thereof and terminating outwardly from the slots of the web, `and said slits imparting flexibility to the ring.

3. A piston ring comprising a slotted annular web having parallel spaced annular flanges extending from opposite sides thereof, and a plurality of vertically registering circiunferentially spaced slits extending radially into said flanges and terminating in substantially circular apertures spaced inwardly of the inner sides thereof.

4. A piston ring comprising a slotted annular `web 4having parallel spaced annular flanges extending from opposite sides thereof, and a plurality of vertically registering circumferentially spaced slits extending radially into said flanges from the outer sides thereof and terminating in substantially circular apertures extending through said flanges inwardly of the inner margins thereof.

5. An oil control piston ring having an annular web with parallel spaced annular flanges extending outwardly from opposite sides thereof, said web having a plurality of radially extending circumferentially spaced oil return slots formed therein and extending partially into said flanges from the inner sides thereof, and a plurality of circumferentially spaced slits extending partially through said flanges from the outer sides thereof `in alignment with, but stopping short of said slots.

6. An oil control piston ring having an annular web with parallel spaced annular flanges extending outwardly from opposite sides thereof, said web having a plurality of radially extending circumferentially spaced oil return slots formed therein and extending partially into said flanges from the inner sides thereof, and a plurality of vertically registering circumferentially spaced slits extending radially into said flanges from the outer sides thereof toward said slots in alignment therewith -but terminating short of said slots.

7. An oil control piston ring having an annular web with parallel spaced annular flanges extending outwardly from opposite sides thereof, said web having a plurality of radially extending circumferentially spaced oil return slots formed therein and extending partially into said flanges from the inner sides thereof, said flanges having a pluralitykof vertically registering uniformly spaced apertures extending therethrough, inwardly of the outer sides thereof and in alignment with said slots, and also having a plurality of spaced slits extending radially into said flanges from the outer sides thereof and terminating at their inner ends in said apertures.

HERBERT F. PRASSE.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 2,183,199 Lutz Dec. l2, 1939 2,267,322 Bowers Dec. 23, 1941 2,273,691 Bowers Feb. 17, 1942 2,346,899 Bowers Apr. 18, 1944 

